1. Field of the Invention
The present invention relates to a bulk silica porous material and a method for producing a bulk silica porous material which has a large crystal size serving to reduce light scattering, which has uniform and adjustable pore size and which can be utilized for optical and electronic functional materials.
2. Description of the Related Arts
Among porous materials, the one having a pore size (herein means the diameter of a pore) ranging from 1 to 10 nm and the pore size distributing in an extremely narrow range is referred especially to as a meso porous material.
Such a meso porous material is used as a material for separation and adsorption of gases and solutions because of its substantially uniform and adequate pore size. Such a porous material is used also as a functional material such as an optical cell or an electronic cell when the pore is packed with metals or semiconductor materials.
The meso porous materials described above are produced, for example, by the ion exchange between Kanemite which is one of lamellar silicates and a surfactant (Japanese Laid-Open Patent Publication 4-238810) or by the hydrothermal synthesis from silica gel and a surfactant in an air-tight pressure vessel.
However, only a meso porous material having a small crystal size can be obtained by a conventional method.
Accordingly, when such a meso porous material is used as an optical functional material, undesirable light scattering leads to only a limited range of application.
When such a meso porous material is used as an electronic functional material, poor processability of the meso porous material leads to the requirement of a special method for obtaining an electrode contact, resulting in inconvenience for handling.
Thus, a meso porous material obtained by a conventional method is difficult to be utilized as an optical or electronic functional material.
The optical functional material mentioned above is one of those employed as starting materials for optical filters, polarization cells, wavelength conversion cells, optical operational cells, and the like.
The electronic functional material mentioned above is one of those employed as starting materials for quantum operational cells, electronic waveguide cells, ultra high density memories, and the like.